Gui Cheng Wang

Study on Forming Mechanism of Surface Hardening in Two-Pass Grinding 40Cr Steel

We had done the two-pass grind-hardening experiment on 40Cr steel using the conventional aluminum grinding wheel on a surface grinder, compared the structure and performance of the hardened layer of one-pass grinding with those of two-pass grinding and analyzed the forming mechanism of two-pass grinding hardened layers. The results show that there are a similar martensite structure and change rules of hardened layer of one-pass grinding and two-pass grinding in spite of the different of initial structures, for martensite has tempered by the action of the creep feed grinding temperature field. The depths of hardened layer, microhardness and wear resistance have further improved, but the maximal compressive residual stress and its influencing depth of hardened layer have decreased. The forming mechanism of the two-pass grinding hardened layer is the same as that of the grinding hardened layer of quenched steel.

Experimental research on grind-hardening of 65Mn steel

Grind-hardening was done on 65Mn steel with a conventional surface grinder and a corundum-grinding wheel. Research was conducted to probe into microstructures and properties of the hardened layer under varied depth of cut and cooling conditions. Results show that the hardened layer does not change noticeably in their martensitic structures and micro-hardness, which is ranged between 810-870HV. When the depth of cut increases or the dry grinding technique is adopted, the hardened layer becomes thicker accordingly. Under the condition of dry grinding with the depth of cut 1.0mm, the hardened layer depth reaches 2.0mm. It can find applications in grinding and metal surface modification field.

Formation and Simulation of Cutting-Direction Burr in Orthogonal Cutting

The cutting-direction burr is one of the important factors that influence the edge quality and performance of precision parts. The cutting-direction burr formation process is simulated with DeformTH3D. The mechanism of cutting-direction burr formation is analyzed in terms of the results of the simulation. The negative shear zone and initiation negative shear angle are discussed too. Study results show that the deformation of CDE is an important factor affect the cutting direction burrs’ size and shape.

Research of Surface Hardening Based on Transverse Feed Grinding

The structure and performance of the hardened layer in this paper has been researched by means of transverse feed grinding 40Cr steel on a plane grinding machine, the result shows that under the action of the grinding temperature field, there are different structural change rules and distributing characteristics of micro-hardness. Although there is always a softened band, which is made up of a transitional area and an unhardened area or a temper area in the hardened layer, the reasonable softened band is conducive to the improvement of wear-resistant quality of a hardened layer under the condition of oil lubrication.

Research and Development of LM Neural Network Prediction System for Grind-Hardening

An improved neural network based on L-M algorithm has been applied to the prediction of the grind-hardening parameters against to the slow convergence rate of conventional BP neural network. And the the neural network model for grind-hardening is established. The neural network prediction system for grind-hardening process has been developed based on L-M algorithm. The functions of system is analyzed, particularly and some pivotal technology to realize the system are put forward.

Study on the Formation of Grind-Hardening of Steel AISI 1066

Grind-hardening was done on Steel AISI 1066 with a conventional surface grinder and a corundum grinding wheel, and research was conducted to probe into structures and properties of the hardened layer under varied depth of cut and cooling conditions. Results show that the hardened layer do not change noticeably in their martensitic structures and micro-hardness, which is ranged between 810870HV; But when the depth of cut increased or the dry grinding technique is adopted, the concentration of martensites and carbonides becomes lower, while the amount of residual austenites increases, and the completely hardened zone gets thicker. This conclusion serves as an experimental basis for the active control of properties of the grind-hardened layer of Steel AISI 1066.

The Imbalance Source of Spindle-Tool System and Influence to Machine Vibration Characteristics

Because of various errors in the process of special structural designing, manufacturing and assembLing, there are varying degrees of unbalanced residual content in machine spindle-tool system. This research presents some kinds of imbalance source of spindle-tool system, on the basis of classification, and then its components dynamic balancing quaLity grade influenced on the balanced state of entire system was demonstrated. By means of machine raising-speed idle running in CNC machine, three cases of testing machine vibration signal and analyzing its characteristics were investigated in turns, including spindle witHout assembLing tool system, the spindle with assembLing perfect balanced tool system and the spindle with various imbalance of tool system. The comparing results and conclusions will provide effective guideLine on the researching about spindle-tool systems imbalance influence to high speed machining stabiLity and processing quaLity.

Application of Castor Oil-Based Cutting Fluids in Precision Turning

Green machining is a process that implements sustainable development strategy. In order to reduce cost and decrease environmental pollution in manufacturing process, a sort of biodegradable castor oil-based emulsion is developed, whose physical and chemical properties can correspond with the national standards. The cooling and lubricating properties of the emulsion are better while machining steel materials through comparative experiments with certain imported commodity synthetic cutting fluid. The emulsion can successfully substitute for commodity fluid because of its high performance-price ratio.

Simulation and Control of Two Side Direction Burr

A finite element model was developed for simulation of two side direction burr formation process. Based on strain distribution, a two side burr formation mechanism was proposed. Burr form and burr size of simulation are close to thats of experiment. Finite element model generated here provided a numerical analysis method to solve the prediction of burr and chip formation and physical insight into the fundamental burr formation mechanism. The stain in two side direction of material near the side face decides the shape and the size of two side direction. Multi-workpieces are machined at the same time with side face closely by each others can control the formation of two side direction strain and two side direction burr.

Thermal Stress Simulation of the Surface Grinding

Thermal stresses of grinding plays an important role on the fatigue and wear resistance of the component. A comprehensive analysis of thermal stress induced by surface grinding has been conducted with aid of the finite element method. To obtain a reliable figure of thermal stress induced by grinding, temperature-dependent properties of workpiece materials were taken into account. The developed finite element procedure has also been applied to calculate the surface and sub-surface thermal stress induced by moving source of triangular heat when convection and radiation is occurred over the whole work. Based on an analysis of the effects of wheel velocity on the thermal stress distributions in an elastic-plastic solid, some important conclusions were given.